ORLANDO, Fla./NEW YORK — Prosecutors in the George Zimmerman trial came under more scrutiny on Tuesday, threatened by a lawsuit from a witness while Attorney General Eric Holder renewed hints the federal government may pick up where the Florida prosecution failed.

A former employee at the Florida State Attorney office is preparing a whistleblower lawsuit against Zimmerman’s prosecutors after testifying that they failed to turn over evidence he obtained from Martin’s cell phone to the defense, his attorney told Reuters.

The shooting in the central Florida town of Sanford on Feb. 26, 2012, prompted street demonstrations last year when police initially declined to arrest Zimmerman, and the verdict provoked renewed marches from critics saying Zimmerman racially profiled Martin as a criminal.

Zimmerman’s defense team have complained repeatedly that race was wrongly injected into the case and that Zimmerman acted in self-defense, accusing civil rights leaders of inflaming racial passions with their calls for a federal investigation of Zimmerman on civil rights grounds.

One of the six jurors, identified only as juror number B-37, told CNN on Monday she did not think Zimmerman racially profiled Martin and believed Martin attacked Zimmerman first. The entire panel — five white women and one Hispanic woman — believed race played no role in the case, she said.

Juror B-37′s interview with CNN, her faced blacked out in silhouette, prompted extreme reactions including death threats on social media.

Holder, the chief U.S. prosecutor and an appointee of President Barack Obama, told the annual convention of the National Association for the Advancement of Colored People in Orlando on Tuesday that his office would continue its investigation of the case, which could possibly lead to federal charges against Zimmerman.

“I,” he said emphatically, “am concerned about this case.”

Holder called for a review of self-defense laws like the one in Florida that appeared to play a role in his acquittal. According to the jury’s instructions, Zimmerman had “no duty to retreat and had the right to stand his ground and meet force with force” if he reasonably feared for his life or great bodily harm.

Holder, who is black, also related personal stories about being racially profiled as a young adult and stopped by police.

“Trayvon’s death last spring caused me to sit down and have a conversation with my own 15-year-old son, like my dad did with me,” Holder said. “This was a father-son tradition I hoped would not need to be handed down.”

More protests planned

Civil rights leader Al Sharpton called a “Justice for Trayvon Day,” planning a further 100 demonstrations in 100 cities on Saturday.

“People from all over the country will gather to show that we are not having a two- or three-day anger fit. This is a social movement for justice,” Sharpton told reporters in Washington.

Lead defense lawyer Mark O’Mara on Monday called the prosecution team a disgrace to the legal profession for holding back evidence that should have been promptly shared with the defense team.

Ben Kruidbos, a former director of information technology at State Attorney Angela Corey’s Tallahassee-area prosecutor’s office, is preparing a whistleblower lawsuit against the prosecutors after testifying that they failed to turn over evidence he obtained from Martin’s cellphone while still employed by Corey.

“We will be filing a whistleblower action in (Florida’s Fourth Judicial District) Circuit Court,” said Kruidbos’ attorney Wesley White, himself a former prosecutor who was hired by Corey but resigned in December because he disagreed with her prosecutorial priorities.

A spokeswoman for Corey referred Reuters to Kruidbos’ termination letter, previously made public, in which Corey’s office accused him of hacking confidential information from state computers.

Kruidbos testified last month in a pretrial hearing that he found embarrassing photos on Martin’s phone that included pictures of a clump of jewelry on a bed, underage nude females, marijuana plants and a hand holding a semiautomatic pistol.